The primary purpose of the study is to evaluate the efficiency of a behavioral assessment technique (BAT) in the prediction of daily drug abuse. The aim of this technique is to determine systematically the cognitive and environmental events that regularly precede drug relapse, thereby establishing reliable predictors of a drug crisis. Previous research has shown that BAT predictions of drug abuse were significantly more accurate than were the addicts' own or than would be expected by chance alone. However, because of methodological problems, there was no clear evidence that the BAT is a better predictor of drug abuse than a counselor. The present study will compare the accuracy of both BAT and counselors in predicting daily drug abuse, using the same subjects. Of special interest will be the prediction of transition drug episodes (drug-taking after one or more weeks without drug use).